should be taken. It is important to know that patients with intestinal disorders can develop hypocobalaminemia due to insufficient absorption, and that hypocobalaminemia on the other hand can cause intestinal mucosal changes leading to diarrhea. Specifically, young dogs with
failure to thrive and/or with chronic diarrhea should be tested for hypocobalaminemia, which can be due to a genetic defect of the cobalamin receptor in the ileum (Imerslund-Gräsbeck syndrome). In all cases with low cobalamin concentrations, treatment is indicated either as weekly cobalamin injection or as daily oral cobalamin supplementation.
Folate is absorbed in the proximal small intestine. Folate malabsorption can be present in patients with significant intestinal disease. Similar to cobalamin, folate can help define the location where biopsy samples should be taken. In contrast to cobalamin, it is not clear if folate supplementation is necessary and beneficial for GI patients.
C-reactive protein (CRP) is an acute phase protein whose elevated concentration generally reflects an inflammatory disease. CRP can be increased in dogs with chronic inflammatory intestinal disorders and might help in monitoring the response to treatment.
It has been reported that an elevated cPLI is associated with a worse outcome in dogs with inflammatory bowel disease and therefore might help the clinician to assess the prognosis of the disease. The exact cause of the cPLI elevation in dogs with IBD is currently unknown, but may be suggestive of IBD-associated pancreatitis.
In summary, laboratory evaluation is always indicated in patients with chronic GIS and in certain patients with acute clinical signs in order to rule out extraintestinal causes of disease, detect complication factors, assess the severity of the disease and provide prognosis for the patient. In all cases with chronic diarrhea, it is recommended to measure hematological parameters, serum biochemical parameters with electrolyte concentrations, serum basal cortisol, bile acid, cobalamin and folate concentrations, and trypsin-like immunoreactivity (TLI). Canine PLI might be helpful to assess the prognosis and CRP to monitor treatment success. Specific gastrointestinal permeability testing and determination of serum or fecal concentration of specific inflammatory markers such as calprotectin and S100A12 are currently not routinely used in veterinary medicine, since their clinical usefulness is not clearly defined.
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